Robert Pozen's students at Harvard Business School frequently ask him how he planned out his career to become president of Fidelity Investments. His response? "There was no grand plan; I backed into my career one step at a time." Here, he explains what his history suggests about career planning and the key things he's learned along the way.

In the years after I graduated from law school, I had no idea that I would ultimately become the president of a financial services giant. I held positions as a law professor, a senior official at the Securities and Exchange Commission, and a partner in a law firm.

But during these early steps in my career, I learned a great deal about myself: I found that I really liked doing deals and managing people, rather than drafting regulations and writing articles. So I accepted a job offer at Fidelity Investments in 1987, when it was still relatively young. I spent the next decade climbing the corporate ladder; in 1997, for a complex set of reasons, I was chosen to be president of the company.

What does my history suggest about career planning? That you can't control the trajectory of your career. There are just too many factors beyond your control that will shape your job options—global economic trends, political elections, and technological changes, just to name a few. So don't commit the hubris of thinking that you can determine your professional glide path.

On the other hand, you can increase your probability of success by approaching your career with the right mind-set—one that recognizes that career planning is a continuous process that has to be actively managed. At each step in your career, you need to ask yourself: What can I do next that will maximize my options in the future?

Gain Transferable Knowledge

This process begins with the choices you make at school. You want your education to provide you with the necessary skills and expertise to succeed in a wide variety of jobs. This means that you need to make smart choice about the courses you will follow. I favor those that involve extensive writing, rigorous analysis, or quantitative skills.

Once you have finished your formal education, search for jobs that will allow you to further expand your transferable knowledge—to help you find your next job. Let's say you take a job putting together airplane leases. Within a few years, you could become the world's expert on the subject; however, this narrow expertise probably won't help you in any other line of work. By contrast, if you take a job that will expand your computer programming skills, you can greatly boost your options for later steps in your career.

Gaining experience outside your home country is another way to develop transferable knowledge. I lived for almost two years in Africa and have spent considerable time in England, Japan, and China. Through those experiences, I learned to deal with different economic, cultural, and political environments—which later helped me evaluate or start business units throughout the world.

Similarly, you can make yourself more attractive to more employers by working in different types of organizations during your career. For-profit companies may be concerned about hiring you if you have spent your entire career in government, for instance. At the top levels of management, publically traded companies often fear that a senior executive at a private company won't be able to adjust to the unique pressures of public shareholders and SEC mandates.

Grow Your Network

As you gain transferable knowledge, remember that that is only one piece of the puzzle: your next step should also help you expand your web of personal relationships with peers. To paraphrase a slogan, "Organizations don't hire people. People hire people." The more people you know, the more people will think of you when a job pops open—even when it is not publicly advertised.

Of course, you can build your network to some degree without changing jobs: you can attend conferences or participate in committees at trade associations. But this sort of event-driven networking pales in comparison with the deep bonds you can develop with your colleagues by working, conversing, and traveling with them.

As you ponder your next career step, then, think about the networking advantages you might gain from it. If you're ambitious, you can expand your network by moving to a new company, or even a new industry; obviously, that would be a momentous decision. More modestly, you can grow your network by accepting a job in another unit of the same firm or by heading an interdisciplinary project staffed by people from multiple units.

In this tough economy and ever-changing world, it is more important than ever to smartly evaluate each step in your career. To prepare for whatever surprises lie ahead, try to make choices today that will maximize your options in the future. Gain transferable expertise—in the classroom or at work—and form close bonds with your peers and colleagues.